LED light with active cooling

ABSTRACT

An LED light system that includes an LED and a synthetic jet actuator to cool the LED as disclosed.

This application is related to U.S. patent application Ser. No.11/676,812 which is a continuation-in-part of U.S. patent applicationSer. No. 10/726,882, which claims priority to U.S. provisional patentapplication Ser. No. 60/459,238 filed Mar. 31, 2003. All of theaforementioned patent applications are incorporated by reference herein.

BACKGROUND

An LED (light emitting diode) generally includes a diode mounted onto adie or chip. The diode is then surrounded by an encapsulant. The diereceives electrical power from a power source and supplies power to thediode. The die can be mounted in a die support. To produce a brighterLED, generally, more power is delivered to the LED.

Many LED lighting systems dissipate heat through a different heattransfer path than ordinary filament bulb systems. More specifically,high power LED lighting systems dissipate a substantial amount of heatvia terminals or through the die attached in a direct die mount device.The conventional heat dissipation systems (i.e. radiating a largepercentage of heat to a front lens of a lamp) do not adequately reduceheat in higher power LED systems. Consequently, high power LED systemstend to run at high operating temperatures.

High operating temperatures degrade the performance of the LED lightingsystems. Empirical data has shown that LED lighting systems may havelifetimes approaching 50,000 hours while at room temperature; however,operation at close to 90° C. may reduce an LED life to less than 7,000hours.

BRIEF SUMMARY OF THE INVENTION

A lamp system can include an enclosure, an LED disposed in theenclosure, a synthetic jet actuator at least partially disposed in theenclosure, and power conditioning circuitry in electrical communicationwith the LED and the synthetic jet actuator. The synthetic jet actuatorgenerates a current of fluid to cool the LED. The power conditioningcircuitry receives source power from a source and delivers a first powerto the synthetic jet actuator and a second power to the LED.

In another embodiment, a lamp includes an enclosure, an electricalconnector attached to the enclosure, an LED disposed in the enclosureand in electrical communication with the electrical connector, and asynthetic jet actuator in electrical communication with the electricalconnector. A connector is configured to electrically connect to anexternal power source. The synthetic jet actuator is arranged in theenclosure to generate a fluid current to cool the LED.

In another embodiment, an LED light assembly includes an LED and asynthetic jet actuator disposed with respect to the LED for creating afluid current to cool the LED. The synthetic jet actuator includes afirst plate, a second plate, a piezoelectric material contacting atleast one of the first plate and the second plate and a flexible hingeconnecting the first plate and the second plate.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings are only for purposes of illustrating embodiments of theinvention and are not to be construed as limiting the invention, whichis defined by the appended claims.

FIG. 1 illustrates a side perspective view, where portions areschematically depicted, of an LED lamp having a heat dissipation system.

FIG. 2 illustrates a top perspective view of the heat dissipation systemof the LED lamp device of FIG. 1.

FIG. 2A illustrates a top perspective view of an alternative embodimentof a heat dissipation system of the LED lamp device.

FIG. 3 illustrates a side perspective view, where portions areschematically depicted, of an alternative example of an LED lamp havinga heat dissipation system.

FIG. 4 illustrates a top perspective view of an alternative example of aheat dissipation system for the LED lamp device of FIG. 1 or FIG. 3.

FIG. 5 illustrates a schematic sectional side view of an alternativeheat dissipation system for an LED lamp.

FIG. 6 illustrates a cross-sectional view taken along lines 6-6 of FIG.5.

FIG. 7 illustrates a cross-sectional view similar to that of FIG. 6.

FIG. 8 illustrates a schematic sectional side view of an alternativeheat dissipation system for an LED lamp device.

FIG. 9 illustrates a detailed view of one of the side plates of FIG. 8.

FIG. 9A illustrates a detailed view of an alternative embodiment of oneof the side plates of FIG. 8

FIG. 10 illustrates a schematic sectional side view of an alternativeheat dissipation system for an LED lamp device.

FIG. 11 illustrates a perspective view of a discharge conduit.

FIG. 12 illustrates a top plan view of an orifice plate.

FIG. 13 illustrates a top plan view of an alternative orifice plate.

FIG. 14 illustrates a top plan view of an alternative orifice plate.

FIG. 15 illustrates a bottom plan view of the orifice plate of FIG. 14.

FIG. 16 illustrates a multiple outlet arrangement for a heat dissipationsystem.

FIG. 17 illustrates a plan view of a portion of a lamp device havinganother alternative heat dissipation system.

FIG. 18 illustrates a cross-section of FIG. 17 taken at line 18-18.

FIG. 19 illustrates a side elevation view of an alternative fluidcurrent generator.

FIG. 20 illustrates a plan view of FIG. 19.

FIG. 21 is a perspective view of an example of an LED lamp thatincorporates a synthetic jet to cool components of the lamp.

FIG. 22 is an enlarged perspective view of a lower portion of the lampof FIG. 21.

FIG. 23 is a perspective view of another example of an LED lamp thatincorporates a synthetic jet to cool components of the lamp.

FIG. 24 is perspective view of another example of an LED lamp thatincorporates a synthetic jet to cool components of the lamp.

FIG. 25 is an enlarged perspective view of the synthetic jet actuatorand electrical components for the lamp shown in FIG. 24.

FIG. 26 is a perspective view of an example of an LED lamp thatincorporates a movable blade to cool components of the lamp.

DETAILED DESCRIPTION OF THE INVENTION

With reference to FIG. 1, an LED lamp 10 generally includes a housing(or frame) 12, a plurality of LEDs, which in FIG. 1 are provided in LEDdevices 14 and in FIG. 3 are shown as chip-on-board devices 16, that arein communication with a heat sink 18. A flexible blade 22 oscillates togenerate a fluid current to cool the LEDs and, perhaps, other electricalcomponents.

The flexible blade 22 is driven, i.e. caused to oscillate, by anelectronic actuator. One example of an electronic actuator ispiezoelectric material 24 that connects to the blade and receives powerfrom a power control module 26 to move the blade to generate a fluidstream that passes over surfaces of the heat sink to cool the LEDs. Withreference to FIG. 2A, another example of an electronic actuator caninclude a coil 82 disposed about a core 84 (depicted schematically)constructed of magnetic material. The embodiment depicted in FIG. 2A,other than not including piezoelectric material, is the same as theembodiments depicted in FIGS. 1-3, and therefore the same referencenumbers have been used. In this example a magnet 86 affixes to a freeend of the blade 22 and the power control module (not depicted in FIG.2A, but the same or similar to the power control modules depicted inFIGS. 1 and 3) delivers AC current to the coil to provide a magneticforce to move the blade from side to side.

With reference to the example depicted in FIG. 1, each LED device 14includes a die or multiple die (not visible) that are received in a diesupport 28. Heat that is generated by the LED device 14 is transferredto the heat sink 18 via the die. The LED device 14 mounts to a support32 that attaches to the heat sink 18. The support 32 can include aprinted circuit board (“PCB”) such as metal core printed circuit board(“MCPCB”), an FR4 PCB having thermal vias, a flexible circuit, as wellas other types of supports upon which LED devices can be mounted. Withreference to the example depicted in FIG. 3, each LED 16 mounts directlyto the support 32 in a chip-on-board configuration. Heat is transferredinto the heat sink 18 through conduction.

The mounting of the LED and the electrical connections on the support 32used to supply power to the LED are known in the art, and therefore needno further description is provided. The LEDs and LED devices can beconventional that are known in the art. In the examples depicted inFIGS. 1-3, the support 32 is mounted to a first surface or under surface34 of the heat sink.

With reference also now to FIG. 2, the heat sink 18 includes the undersurface 34 and a second or upper surface 36, which acts as a fluid flowpath surface for dissipating the heat generated by the LEDs. The heatsink can be made from a material having a high coefficient of thermalconductivity, e.g. aluminum and/or copper. Preferably, the heat sink 18includes a material having a coefficient of thermal conductivity greaterthan about 50 W/m K. The heat sink is also preferably made from alightweight thermally conductive material such as a graphite composite,aluminum, a thermally conductive plastic, and the like. The uppersurface provides a heat dissipating surface over which a fluid, mostlikely air, will flow to facilitate heat dissipation. The heat sink 18can be a separate thermally conductive component of the lamp 10 (seeFIG. 3), or it can be an integral thermally conductive component withone of the components of the lamp, for example the housing 10, which canalso include materials having a coefficient of thermal conductivitygreater than about 20 W/m K (for example steel or thermally conductiveplastic materials). The heat sink can also include the structure towhich the LED mounts, including the PCB or similar structure.

In the embodiment depicted in FIGS. 1-3, a pedestal 38 extends upwardlyfrom and normal to the upper surface 36 of the heat sink 18. As shown,the pedestal 38 is the same width as the heat sink 18; however, thepedestal need not be the same width as the heat sink. The pedestal 38has a pedestal surface 40 on which the blade 22 is mounted, The pedestalsurface 40 is spaced from the upper surface 36 an adequate amount toallow the blade 22 to flap or oscillate. Accordingly, the length andcharacteristics of the blade can limit the difference in elevationbetween the pedestal surface 40 and the upper surface 36, and viceversa. The pedestal 38 can be solid, in that it does not contain anypassages through which fluid can flow between the upper surface 36 andthe blade 22, at the point of attachment between the fan and thepedestal. Similarly, the pedestal 38 can also be hollow and the wallsthat depend from the upper surface 36 can prevent fluid flow at thepoint of attachment between the fan and the pedestal. In FIGS. 1 and 2,the pedestal 38 is located at an end of the heat sink 18. Alternatively,the pedestal 32 can be more centrally located on the heat sink 18. Inthis alternative, a blade or a plurality of blades can cantilever offeach side of the pedestal 38 and, thus, over the upper surface 36. Theblade 22 is shown mounted to a central portion of the pedestal 38;however, the blade can mount elsewhere on the pedestal.

As stated earlier, the heat generated by the LEDs is transferred throughthermal conduction to the heat sink 18. To cool the heat sink, air orsome other fluid, is moved over and around the surfaces of the heatdissipating structure. The blade 22 facilitates the movement of suchfluid over the heat sink.

The blade 22 and the piezoelectric material 24 make up a device that iscommonly referred to as a piezoelectric fan. The blade is arranged inthe housing 12 so that it does not obstruct light emanating from theLEDs. The blade is made of a flexible material, preferably a flexiblemetal. An unattached (free) end 42 of the blade 34 cantilevers away fromthe pedestal 38 and over the upper surface 36. The blade mounts to thepedestal surface 40 such that the unattached end 42 of the blade 22 doesnot contact the upper surface 36 when the blade is moving. In FIGS. 1and 2, the blade is mounted directly to the heat sink. Alternatively,the blade can mount to another component of the lamp. In thisalternative, the blade mounts to a portion of the lamp near the heatsink so that the blade can generate an airflow around the exteriorsurfaces of the heat sink. Furthermore, the blade in FIGS. 1 and 2 ismounted such that it moves up and down; however, a blade can mount suchthat it moves side to side, or in another axis, for example diagonally.

The piezoelectric material 24 attaches to the blade 22 opposite theunattached end 42 and over the pedestal 38. Alternatively, thepiezoelectric material 24 can run the length, or a portion of thelength, of the blade 22. The piezoelectric material 24 comprises aceramic material that is electrically connected to a power controlmodule 26 in a conventional manner.

As electricity is applied to the piezoelectric material 24 in a firstdirection, the piezoelectric material expands, causing the blade 22 tomove in one direction. Electricity is then applied in the alternatedirection, causing the piezoelectric material 24 to contract and movingthe blade 22 back in the opposite direction. The alternating currentcauses the blade to move back and forth continuously.

The power control module 26 in the depicted embodiment is configured toreceive AC power from a source and to deliver DC power to the LEDs andto deliver AC power to the piezoelectric material. If desired, AC powercan be delivered to the LEDs, but care should be taken to minimize thereverse biasing of the LEDs. The power control module 26 can includecircuitry and power conditioning components, e.g. a rectifier and avoltage regulator, to condition the source power that is received. Thepower control module can convert higher voltage AC power to lowervoltage DC power to drive the LEDs. The power control module can alsoremove any spikes or surges from the AC source power and deliver acleaner AC power to the piezoelectric material. The power control module26 can be arranged in the housing 12 of the lamp 10 (see FIG. 1) or itcan be remote from the housing 12 (see FIG. 3) and electricallyconnected to the piezoelectric material 24 and the LEDs.

The lamp 10 can include a translucent cover or lens 44 (shown only inFIG. 3) that attaches to the housing 12 and covers the LEDs. The housing12 can also be generally closed having a fluid inlet 46 (depictedschematically in FIG. 1) and a fluid outlet 48. Cool air is drawn inthrough the inlet 46 and hot air is expelled through the outlet 48. Theinlet 46 and the outlet 48 may be covered with filters, respectively, toinhibit the intrusion of dust into the housing.

During operation of the lamp 10, each LED generates heat. The heat fromthe LED conducts into the heat sink 18. Meanwhile, an alternatingcurrent is supplied to the piezoelectric material 24 causing the blade22 to move oscillate, which results in a fluid current moving around theheat sink. The flow of fluid around the heat sink cools the heat sinkmore quickly as compared to having no moving fluid. Accordingly, moreheat can be dissipated from the LEDs resulting in a lower operatingtemperature. Furthermore, the footprint of the lamp can be reducedbecause the size of the heat sink can be reduced due to the activecooling caused by the moving blade. Also, a quiet active cooling takesplace because the piezoelectric fan does not generate a lot of noise,which would be unattractive to consumers.

With reference now to FIG. 4, a heat dissipating system 50 of an LEDlamp is disclosed. The LED lamp includes an LED array (not visible butmade up of LED devices 14 shown in FIG. 1 or LEDs 16 shown in FIG. 3). Apair of fans 58 mounts to the heat dissipating structure (heat sink) 56.Alternatively, only one fan can mount to the heat dissipating structureor a plurality of fans can mount to the heat dissipating structure. Heatgenerated by LEDs is transferred to the heat dissipating structure 56through a die (not visible).

The heat dissipating structure 56 includes a first or lower surface 64to which the LED array is mounted. The heat dissipating structure 56also includes a second or upper surface 66 opposite the lower surface64. Fins 68 project upwardly and substantially normal to the plane ofthe upper surface 66. The upper surface 66 and the surface area of thefins 68 provide a flow path surface over which a fluid, most likely air,will flow to facilitate heat dissipation. The fins 68 increase thesurface area of flow path surface.

The heat dissipating structure 56 also includes a pedestal 70 projectingupwardly from the upper surface 66 of the heat dissipating structure 56.The pedestal 70 also projects upwardly substantially normal to the planeof the upper surface 66 away from the lower surface 64. The pedestal 70is similar to the pedestal 30 described with reference to FIGS. 1-3. Thepedestal 70 is spaced from the fins 68 such that a gap 72 is definedbetween an end of each of the fins and the pedestal. The pedestal 70includes a pedestal surface 74 that is elevated above the fins 68.

The piezoelectric fans 58 are mounted on the pedestal surface 74. Eachfan 58 includes piezoelectric material 76 and a blade 78. Eachpiezoelectric fan 58 is similar to the piezoelectric fans describedabove with reference to FIGS. 1 and 2. An unattached end 80 of eachblade 78 cantilevers away from the pedestal 70 and over the fins 68.Each blade 58 is spaced from the each of the fins 68 so that when eachblade 78 moves up and down the unattached end 80 does not contact thefins. Also, the pedestal 70 can extend upwardly where the fans 58 aredisposed between the fins 68, as opposed to over the fins. Similar tothe piezoelectric fan shown in FIGS. 1 and 2, each fan 58 has thepiezoelectric material 76 attached to the blade 78 opposite theunattached end 80 and over the pedestal 70.

With reference to FIG. 5, a current generator 110 is disposed in a wall112. The current generator creates a substantially vortex-shapedcurrent; however, the current generator is not limited to creating asubstantially vortex-shaped current, but should be construed to includeany device that can create a fluid current of any configuration. Thewall 112 can form a portion of the heat dissipating structure (heatsink) of an LED lamp described with reference to FIGS. 1-4. The wall 112can also include the structure to which an LED is mounted, such as aprinted circuit board. The wall includes a flow path surface 114 overwhich fluid circulates to cool the wall.

A generally rectangular cavity 116 having a depth D (FIG. 6), width W(FIG. 6), and length L is formed in the wall 112. The cavity 116 has apair of spaced-apart generally parallel side walls 118 and 120 (FIG. 6)and a pair of spaced-apart generally parallel end walls 122 and 124. Thewalls define an opening 126 in the flow path surface 114. The opening126 of the cavity 116 is covered by a flexible, generally rectangularactuator blade 128.

The blade 128 is attached to the wall 112 by a cantilever support atfirst end of the cavity 116. Alternatively the blade 128 could alsoattach to the wall 112 an opposite end of the cavity 116. The blade 128can attach to the wall 112 in any conventional manner, for example withan adhesive or fasteners. The blade 128 includes two layers: a flexiblelayer 130 formed from a flexible material, such as stainless steel oraluminum, and a piezoelectric layer 132 attached to the flexible layer130 and formed from a piezoelectric material, for example piezoceramic.The piezoelectric layer 132 is disposed closest to the flow path surface114; however, the piezoelectric layer 132 can be disposed opposite theflow path surface. Although the illustrated example shows a singlepiezoelectric layer 132, a second layer piezoelectric layer can attachto the opposite side of the blade 128, so that the flexible layer 130would have a piezoelectric layer on each side. The layers 130 and 132are securely bonded to each other, for example by the use of an adhesivelayer. Also the layers 130 and 132 are substantially the same length. Asseen in FIG. 6, the width of the blade 128 is less than the width W ofthe cavity 116. As seen in FIG. 5, the length of the portion of theblade 128 extending over the cavity 116 is slightly less than the lengthL of the cavity 116 to provide an operating clearance. The length L ofthe cavity 116 (and thus the length of the blade 128) can be varied,although the shorter the blade and/or cavity become, the smaller the tipdeflection of the blade 128 and thus the lower the effectiveness of thecurrent generator 110.

In one embodiment the length L of the cavity can be about 10 inches.This is significantly larger than known similar devices. The blade 128is installed in an off-center position relative to the cavity 116 suchthat two unequal side gaps 134 and 136 are created between the edges ofthe blade 128 and the side walls 118 and 120 of the cavity 116. Theblade 128 is also connected to a controllable electric source 138(depicted schematically in FIG. 5) to supply an alternating voltage ofthe desired magnitude and frequency to the blade 128. The controllableelectric source 138 can also supply direct current voltage to the LEDsthat are in thermal communication with the wall 112.

In operation, an alternating voltage is applied to the blade 128 fromthe controllable source. When a potential is applied across thepiezoelectric layer 132, the layer 132 either expands or contractsdepending upon the polarity of the voltage. Since the piezoelectriclayer 132 is bonded to the flexible layer 130, the application of thealternating voltage induces a bending strain resulting in oscillation ofthe blade 128.

In one example, a blade 128 approximately 25.4 cm (10 in.) long, 25.4 mm(1 in.) wide, and 3.43 mm (0.135 in.) thick, having a flexible layer 130of stainless steel 3.18 mm (0.125 in.) thick was constructed. When a 75Hz, 200V RMS sinusoidal input signal was applied, the peak-to-peak tipdeflection at the unattached end of the blade 128 was approximately 1.27mm (0.5 in.). This tip deflection is somewhat greater than prior artdevices and increases the capacity of the current generator 110.Furthermore, the use of a piezoceramic actuator has advantages overother known types of actuators, such as mechanical actuators,particularly in that it may be reliably operated at higher frequencies,for example about 70-80 Hz, which further increases the effectiveness ofthe current generator 110. A mechanically actuated device has problemsoperating at these frequencies because it tends to distort the bladeinto a sinusoidal mode shape, which interferes with the creation of thedesired vortex patterns. The piezoelectrically actuated blade 128 ofthis example does not experience this problem.

In operation, as the blade 128 moves outward with respect to the cavity116, increasing the cavity volume, ambient fluid is drawn from largedistances from the large side gap 136 into the cavity 116. On thesubsequent down stroke, the blade 128 moves downward into the cavity116, decreasing the cavity volume and expelling fluid from the cavitythrough the large side gap 136. As shown in FIG. 7, this alternating“pull” and “push” of the blade 128 results in a vortex flow patternabove the large side gap 136, illustrated by arrow B. A similar flowpattern, to a lesser degree, is created above the narrow side gap 134,illustrated by arrow C. The larger side gap 136 forms the primarypassage for fluid into and out of the cavity 116, while the narrow sidegap 134 primarily creates a space for operating clearance of the blade128 as it oscillates. In the case where the flow over the surface of thewall 112 is opposite to the direction of arrow A, there is an additionalbenefit in that when the current generator blade is extended outward, itacts as a conventional vortex generator protruding from the surface,helping to prevent flow separation. Also the end wall 124 prevents axialcurrent flow below the flow path surface 114.

Referring to FIG. 8, a synthetic jet actuator 140 is disposed in a wall142. The synthetic jet also generates a current similar to the fan andthe current generator described above. A current generator body 148 isattached to an orifice plate 144 by a discharge conduit 150, which is anextension of a flexible hinge 156, described below. The orifice plate144 is disposed in the wall 142 flush with a flow path surface 146. Theinterior of the current generator body communicates with the flow pathsurface 146 of the wall 142 through one or more orifices 152 in theorifice plate 144.

The current generator body 148 is constructed from a pair of side plates154 that are connected by the flexible hinge 156. The plates 154 arespaced apart from each other and are disposed in a generally parallelrelationship. The flexible hinge 156 surrounds the periphery of eachplate 154 and can overlap the edges of the plates 154. The hinge 156holds the side plates 154 together. An internal fluid cavity 158 is thusenclosed by the side plates 154 and the hinge 156. Each side plate 154can be a circular disk or other shapes, for example rectangular. Thisarrangement is similar to a bellows. The hinge 156 can be constructedfrom any flexible, fluid-tight material. The hinge can also be made of amaterial that is suitable as an adhesive, for example a room temperaturevulcanizing (RTV) material, an elastomer, or other flexible material.

The orifices 152 may be a series of holes as shown in FIG. 12, or maytake the form of an elongated slot, as shown in FIG. 13. The size,shape, number and angle of the orifices 152 can be modified in order tosuit a particular application, for example the orifices 152 can beangled in a downstream direction (pitch angle), or the array of orifices152 can be angled in the plane of the orifice plate 144 (yaw angle).

Referring to FIG. 9, each side plate is formed from a pluralitygenerally planar stacked layers. Each side plate 154 forms a bimorphpiezoelectric structure; each side plate comprises two piezoelectriclayers 160 and 162 having opposite polarities. The piezoelectric layers160 and 162 are made of a piezoceramic material. When a voltage isapplied to the bimorph piezoelectric structure, one layer 160 expandswhile the other layer 162 contracts due to the opposite-facingpolarities. Since the piezoelectric layers 160 and 162 are parallel toeach other, the application of a voltage causes the side plate 154 totake up a roughly hemispherical shape, in the case of circular sideplates. When a voltage of opposite polarity is applied, the side plate154 bends in the opposite direction (i.e. concave instead of convex).This arrangement in effect doubles the force exerted for a given voltagecompared to a single piezoelectric layer.

The piezoelectric layers 160 and 162 are covered on each side with athin protective cladding layer 164 to prevent cracking of thepiezoelectric layers 160 and 162. In an exemplary embodiment thecladding layers 164 are made of stainless steel, preferably very thin,and are attached to the piezoelectric layers 160 and 162 with a suitableadhesive. The piezoelectric layers 160 and 162 with the attachedcladding layers are attached to opposite sides of a central layerreferred to as a shim 166, for example with an adhesive layer. The shim166 material and thickness is selected for sufficient stiffness to placethe operating frequency of the actuator body 148 in the desired range.In the illustrated example, the shim 166 is made of aluminum. The sideplates 154 are connected to a controllable electric source 168 (shownschematically in FIG. 4) so that an alternating voltage of the desiredmagnitude and frequency may be applied to the blade side plates 154.

In operation, voltage from the electric source is applied to the sideplates 154 so as to cause the plates to deflect in opposite directionsto each other. That is, when the left-hand side plate 154 illustrated inFIG. 9 is deflected convexly to the right, the right-hand side plate 154is deflected convexly to the left. This simultaneous deflection reducesthe volume of the fluid cavity 158 and causes fluid to be expelledthrough the discharge conduit 150 and then from the orifice 152. Whenvoltage of opposite polarity is applied, the side plates deflect in theopposite direction. This action increases the volume of the fluid cavity158 and causes a decreased partial pressure in the fluid cavity 158,which in turn causes fluid to enter the fluid cavity 158 through theorifice 152. Since each side plate 154 is a bimorph piezoelectricstructure, and there are two side plates, this embodiment of the presentinvention has four times the capacity of a single piezoelectric deviceof the same overall dimensions. Fluid can expelled from the orifice 152in a multitude of directions by simply changing the orientation and/orconfiguration of the plates, the flexible hinge or the orifice.Furthermore, the synthetic jet actuator 140 can be used to directly coolan LED die that does not include a heat sink or a larger heatdissipating structure.

With reference to FIG. 9A, alternatively the each side plate 154 canhave a unimorph construction in that each side plate has a singlepiezoelectric material 160 that is located on an external surface of theside plate. The remainder of the construction is similar to theconstruction of the synthetic jet described above in that it can includethe shim 166 and the protective layer(s) 164.

The output of two or more of the current generator bodies 148 can becombined into a single discharge area. As seen in FIG. 10, a syntheticjet actuator 170 comprises, for example, a pair of current generatorbodies 148 disposed adjacent a wall 142. A discharge conduit 172 havinga generally inverted Y-shape connects the two current generator bodies148. The conduit 172 is shown in more detail in FIG. 11. The conduit 172is hollow and has an outlet leg 174 connected to two inlet legs 176 at ajunction 178. The outlet leg 174 of the conduit 172 communicates withthe flow path surface 146 of the wall 142 through one or more orifices152 in the orifice plate 144. The orifices 152 may be a series of holes,as shown in FIG. 12, or may take the form of an elongated slot as shownin FIG. 13. The size, shape, number and angle of the orifices 152 may bemodified in order to suit a particular application. The orifices 152 mayalso be arranged in the pattern illustrated in FIGS. 14 and 15, asdescribed in more detail below. With reference back to FIG. 10, thecurrent generator bodies 148 are connected to a controllable electricsource 180 (shown schematically). It should be noted that it is possibleto use one power source 180 for multiple current generator bodies 148connected in series, because each current generator body 148 has a lowpower consumption. This variation of the invention provides furtherincreased capacity from a single orifice plate.

An alternative orifice plate 184 is illustrated in FIGS. 14 and 15. FIG.14 illustrates the side facing the flow path surface 146, and FIG. 15illustrates the side facing the fluid cavity 158 of the currentgenerator body 148. The orifice plate 184 has a central hole 186 andside holes 188 disposed on either side of the central hole 186. Each ofthe holes has a conical or nozzle-like profile, so that the hole inlet190 is larger in diameter than the hole outlet 192. The central hole 186is disposed so that the inlet 190 is on the side of the orifice plate184 facing the fluid cavity 158 (FIG. 14) of the current generator body148, while the two side holes 188 face the opposite direction. Since theholes have a lower resistance to flow in the direction from the inlet190 to the outlet 192 than in the opposite direction, this arrangementtends to make air going inward to the fluid cavity 158 flow through thetwo side holes 188, while flowing outward from the fluid cavity 158tends to flow though the central hole 186. This increases the velocityof the air flow out of the fluid cavity 158 which increases theeffectiveness of the synthetic jet actuator 140.

As an alternative to the arrangement illustrated in FIG. 8, the currentgenerator body 148 can be provided with more than one outlet. Forexample, with reference to FIG. 16, a plurality of discharge conduits194 may be arranged around the periphery of a current generator body.FIG. 16 depicts how these additional discharge conduits 194 could beincorporated into a flexible hinge 196, which is seen from the side inFIG. 16. The number of discharge conduits 194 is only limited by thephysical space available. Although the outlet velocity is reduced byadding additional discharge conduits 194, the outlet velocity is notreduced in proportion to the number of additional discharge conduits194. For example, testing has shown that a current generator body 148having 6 outlets still produces about 90% of the outlet velocity of thesame current generator having a single outlet. In other words, a singlecurrent generator body 148 could be used to produce output for a numberof orifices 152.

For example, as shown in FIG. 17, a fluid current generator 200 includesa plurality of openings 202 to cool a heat sink 204 of an LED assembly.With reference to FIG. 18, the fluid current generator 200 includes apair of flexible side plates 206 attached to or including piezoelectricmaterial, similar to that depicted in FIG. 8. Piezoelectric material ischarged to move the flexible side plates. A flexible hinge 208 connectsthe pair of plates; and the flexible hinge includes the plurality ofopenings 202. Also, the heat sink 204 includes a plurality of fins 212extending from a base 214 of the heat sink. The fins 212 radiate fromthe center of the heat sink, and the fluid current generator 200 issituated at or near the center of the heat sink. Such a configurationcan be used to cool an LED array similar to array described with respectto FIGS. 1-4.

In another alternative embodiment, a plurality of synthetic jets isshown in FIGS. 19 and 20. In this embodiment, side plates 220 attach toone another by flexible hinge 222. The flexible hinge can be onecontiguous piece, or it can comprise a plurality of distinct hingepieces connecting one or two side plates together, for example. Theflexible hinge can include a plurality of openings 224 that can directcurrent flow to different locations. For example, one opening 224 can beprovided for the space between two adjacent side plates 220.Alternatively, more than one opening could be provided for such a space.

The fluid current generators described above can be used to coolportions of an LED light assembly. One fluid current generator can beused to cool one or a few LEDs. Alternatively, multiple LED systems canemploy a heat sink, and the fluid current generators described above canbe used to move current over the surface of the heat sink to cool theLEDs.

With reference to FIG. 21 a more specific example of an LED lamp 310that incorporates a synthetic jet to cool portions of the lamp is shown.An example on an LED lamp that does not include a synthetic jet to coolportions of the lamp, but does include many other components of the lampshown in FIG. 21 is disclosed in WO 2004/100213, which is incorporatedby reference herein. The lamp 310 includes an enclosure, which in theembodiment depicted in FIG. 21 is a bulb 312 that is similarly shaped toa conventional bulb found in incandescent lamps. The bulb 312 is shownas transparent for clarity. The bulb 312 can be coated with phosphor 314that is contained within a light transmissive medium, e.g. the bulb.This allows for the use of a UV/Blue LED 316 and a phosphor or blend ofphosphors, for converting LED-generated ultraviolet (UV) and/or bluelight into white light for general illumination purposes. It should beappreciated, however, that the invention is also suitable to theconversion of light from other light sources to light of a differentwavelength. Furthermore, LED devices that are capable of generatingwhite light can also be used which would obviate the need for thephosphor layer.

As discussed above, LEDs 316 are used to generate light, as compared toa filament that is used in a standard incandescent lamp. The LEDs 316mount to a printed circuit board (“PCB”) 318 (or other support such asthose described above). The PCB 318 is disposed in the enclosure. Withreference to FIG. 22, power conditioning electronics 322 mount to alower surface 324 of the PCB 318 and the LEDs 316 (FIG. 21) mount to theupper side 326 of the PCB. The power conditioning electronics are inelectrical communication with the LEDs and are configured to converthigher voltage AC power to a lower voltage DC power for driving the LEDs316. Alternatively, the power conditioning electronics can be configuredto convert higher voltage AC power to a lower voltage AC power fordriving the LEDs 316 while limiting the reverse bias on the LEDs. Thepower conditioning electronics 322 are also in electrical communicationwith an Edison base 328, which is depicted schematically by a wire 332.The Edison base 328 provides an electrical connection between theelectrical components of the lamp 310 and an external power source,which is typically 120 VAC. Alternatively, the Edison base can bereplaced with another electrical connector, for example a bi-pinconnector, that is attached to the enclosure to provide for theelectrical connection to the external power source for the lamp 310.

A synthetic jet 340 is disposed in the enclosure 312 to cool the LEDs316 and the electronics. The synthetic jet 340 is similar to thesynthetic jets that are described above. The synthetic jets 340 includeside plates 342 that attach to one another by flexible hinge 344. Theflexible hinge can be one contiguous piece, or it can comprise aplurality of distinct hinge pieces connecting one or two side platestogether, for example. The flexible hinge 344 includes an opening 346through which fluid is expelled and directed towards the PCB 316 to coolthe LEDs and the power conditioning electronics. The synthetic jet 340connects to a mounting bracket 348 that, in the depicted embodiment, islocated aligned with a symmetrical axis of the lamp.

The synthetic jet 340 is also in electrical communication with theEdison base 328. Wires 352 provide the electrical connection between theEdison base 328 and the synthetic jet. Power conditioning electronicscan be located in the circuit that connects the synthetic jet 340 to theEdison base 328 to condition the input AC power to remove voltagespikes, and the like, to provide a cleaner sinusoidal wave AC power tothe synthetic jet. These power conditioning electronics can be found ina module that is surrounded by the Edison base.

To allow for the ingress of cool air and the egress of hot air, a filter354 covers a vent in formed in the enclosure 312. The filter 354 canalso be located where the Edison base 328 meets the bulb 312 and can beattached to or integrally formed with the Edison base.

With reference to FIG. 23 another example of an LED lamp 370 thatincorporates a synthetic jet to cool portions of the lamp is shown. Thislamp 370 includes a reflector housing 372 that is shaped similar to aconvention PAR lamp. The reflector housing 372 is shown as translucentin FIG. 23 for clarity. The reflector housing 372 is made of glass andprovides an enclosure for a light source, which will be described inmore detail below. The reflector housing is coated with a reflectivecoating. The reflector housing includes a reflective portion 374, alongat least an inner surface thereof and is preferably a highly reflectivematerial such as an aluminum layer, although other reflective surfacessuch as a dichroic material can be used without departing from the scopeand intent of the present invention. The reflective portion 374typically has a concave or parabolic shape, although it is contemplatedthat the reflector housing could adopt a different contour or shape suchas an elliptical or other known shape or combination of shapes. Thereflector housing further includes a heel portion 376 that dependsaxially outwardly from a central portion of the reflective portion 374and has a substantially cylindrical configuration. The heel portion 376attaches to a lamp base, such as an Edison base 380. A lens cover 378encloses the reflector housing along the outer circumference of thehousing. The lens cover 378 can be coated with phosphor similar to thebulb described in FIGS. 21 and 22.

LEDs 386 are used to generate light. The LEDs 386 mount to a printedcircuit board (“PCB”) 388 (or other support such as those describedabove). The PCB 388 is disposed in the reflector housing 372. Powerconditioning electronics 392 mount to a lower surface 394 of the PCB 388and the LEDs 386 mount to the upper side 396 of the PCB. The powerconditioning electronics are in electrical communication with the LEDsand are configured to convert higher voltage AC power to a lower voltageDC power for driving the LEDs. Alternatively, the power conditioningelectronics can be configured to convert higher voltage AC power to alower voltage AC power for driving the LEDs while limiting the reversebias on the LEDs. The power conditioning electronics are also inelectrical communication with an Edison base 380, which is depictedschematically by a wire 398.

A synthetic jet 400 is disposed in the reflector housing 372 to cool theLEDs and the electronics. The synthetic jet 400 is similar to thesynthetic jets that are described above. The synthetic jet 400 connectsto a mounting bracket 402 that, in the depicted embodiment, is locatedaligned with a symmetrical axis of the lamp. Similar to the embodimentdepicted in FIGS. 21 and 22, the synthetic jet 400 is also in electricalcommunication with the Edison base 380. Wires 404 provide the electricalconnection between the Edison base 380 and the synthetic jet. Powerconditioning electronics can be located in the circuit that connects thesynthetic jet 400 to the Edison base 380 to condition the input AC powerto remove voltage spikes, and the like, to provide a cleaner sinusoidalwave AC power to the synthetic jet. These power conditioning electronicscan be found in a module that is surrounded by the Edison base.

To allow for the ingress of cool air and the egress of hot air, a filter406 covers a vent in formed in the reflector housing 372. The filter 404can also be located where the Edison base 380 meets the heel 376 and canbe attached to or integrally formed with the Edison base.

With reference to FIG. 24 another example of an LED lamp 410 thatincorporates a synthetic jet to cool portions of the lamp is shown. Thelamp 410 includes an enclosure, which in the embodiment depicted in FIG.24 is a bulb 412 that is similarly shaped to a conventional bulb foundin incandescent lamps. The bulb 412 is shown as transparent for clarity.The bulb 412 is coated with phosphor 414 that is contained within alight transmissive medium, e.g. the bulb. This allows for the use of aUV/Blue LED and a phosphor or blend of phosphors, for convertingLED-generated ultraviolet (UV) and/or blue light into white light forgeneral illumination purposes. It should be appreciated, however, thatthe invention is also suitable to the conversion of light from otherlight sources to light of a different wavelength. Furthermore, LEDdevices that are capable of generating white (or other color) light canalso be used which would obviate the need for the phosphor layer.

As discussed above, LEDs are used to generate light, as compared to afilament that is used in a standard incandescent lamp. The LEDs (notvisible, but are the same as or very similar to the LEDs 316 shown inFIG. 21) mount to a printed circuit board (“PCB”) 418 (or other supportsuch as those described above) and are disposed beneath a lens 416 thatmounts overtop the LEDs. The PCB 418 is disposed in the enclosure.

Power conditioning electronics 422 are provided on a second PCB 424 thatis spaced from the first PCB 418. The power conditioning electronics arein electrical communication with the LEDs and are configured to converthigher voltage AC power to a lower voltage DC power for driving theLEDs. Alternatively, the power conditioning electronics can beconfigured to convert higher voltage AC power to a lower voltage ACpower for driving the LEDs while limiting the reverse bias on the LEDs.The power conditioning electronics 422 are in electrical communicationwith an Edison base 428 so that they receive external AC power. Thepower conditioning electronics 422 are also in electrical communicationwith the LEDs depicted schematically by a wire 432.

A synthetic jet 440 is disposed in the enclosure 412 to cool the LEDsand the electronics. The synthetic jet 440 is similar to the syntheticjets that are described above. The synthetic jets 440 include sideplates 442 that attach to one another by flexible hinge 444. Theflexible hinge can be one contiguous piece, or it can comprise aplurality of distinct hinge pieces connecting one or two side platestogether, for example. The flexible hinge 444 includes openings 446through which fluid is expelled and directed towards the first PCB 418to cool the LEDs and towards the second PCB 424 to cool the powerconditioning electronics 422. The synthetic jet 440 connects to amounting bracket 448 that, in the depicted embodiment, extends from thesecond PCB 424.

The synthetic jet 440 is also in electrical communication with theEdison base 428 through the power conditioning electronics 422. Wires452 provide the electrical connection between the power conditioningelectronics 424 and the synthetic jet. Power conditioning electronics424 also condition the input AC power to remove voltage spikes, and thelike, to provide a cleaner sinusoidal wave AC power to the syntheticjet.

To allow for the ingress of cool air and the egress of hot air, filters454 cover respective vents in formed in the enclosure 412. At least oneof the filters 454 can also be located where the Edison base 428 meetsthe bulb 412 and can be attached to or integrally formed with the Edisonbase.

In the example embodiments depicted in FIGS. 21-25, the synthetic jetactuator can take other configurations that those shown. For example,the synthetic jet actuator can include a flexible diaphragm mountedaround its periphery to a rigid housing defining an internal chamber.The diaphragm includes an orifice. The diaphragm moves in and out of theinternal chamber as it is being actuated by a piezoelectric actuator.Also, the synthetic jet actuator can take the configuration of thesynthetic jet actuators described in FIGS. 8-20. Moreover, bases otherthan the Edison base that is disclosed can be used to electricallyconnect the lamp to an external source of power.

With reference to FIG. 26 another example of an LED lamp 510 thatincorporates a piezofan to cool portions of the lamp is shown. A bladethat is driven by electromagnetic force, similar to the embodiment shownin FIG. 2A, can also be utilized in lieu of the piezofan. The lamp 510includes an enclosure, which in the embodiment depicted in FIG. 26 is abulb 512 that is similarly shaped to a conventional bulb found inincandescent lamps. Alternatively, the lamp can have the configurationsimilar to a PAR lamp, such as that described in FIG. 23, with theremainder of the components being the same or very similar to that whichwill be described below. The bulb 512 is shown as transparent forclarity. The bulb 512 can be coated with phosphor 514 that is containedwithin a light transmissive medium, e.g. the bulb. This allows for theuse of a UV/Blue LED 516 and a phosphor or blend of phosphors, forconverting LED-generated ultraviolet (UV) and/or blue light into whitelight for general illumination purposes. It should be appreciated,however, that the invention is also suitable to the conversion of lightfrom other light sources to light of a different wavelength.Furthermore, LED devices that are capable of generating white light canalso be used which would obviate the need for the phosphor layer.

As discussed above, LEDs 516 are used to generate light, as compared toa filament that is used in a standard incandescent lamp. The LEDs 516mount to a printed circuit board (“PCB”) 518 (or other support such asthose described above). The PCB 518 is disposed in the enclosure. Powerconditioning electronics 522 (schematically depicted) mount to an uppersurface 524 of the PCB 518 and a heat sink 526 contacts a lower surfaceof the PCB. The heat sink 526 is similar to those described above, andcan include fins (even though none are shown). Heat from the LEDs 516 istransferred into the heat sink.

The power conditioning electronics 522 are in electrical communicationwith the LEDs and are configured to convert higher voltage AC power to alower voltage DC power for driving the LEDs 516. Alternatively, thepower conditioning electronics can be configured to convert highervoltage AC power to a lower voltage AC power for driving the LEDs 516while limiting the reverse bias on the LEDs. The power conditioningelectronics 522 are also in electrical communication with an Edison base528, which is depicted schematically by a wire 532. The Edison base 528provides an electrical connection between the electrical components ofthe lamp 510 and an external power source, which is typically 120 VAC.Alternatively, the Edison base can be replaced with another electricalconnector, for example a bi-pin connector, that is attached to theenclosure to provide for the electrical connection to the external powersource for the lamp 510. The power conditioning electronics can also belocated elsewhere in the lamp 510, for example in the Edison base or ona separate PCB (for example similar to the configuration depicted inFIG. 24).

A blade 540 is disposed in the enclosure 512 to cool the LEDs 516 andthe electronics by passing a current over a surface or surfaces of theheat sink 526. The blade 540 is similar to the blades that are describedabove. Piezoelectric material 544 attaches to the blade. A wire 542 isshown connected to the piezoelectric material 544 and the Edison base528. This can provide AC line voltage to the piezoelectric material 542to drive the blade back and forth. Alternatively, the piezoelectricmaterial can be in electrical communication with the power conditioningelectronics 522 or with another power conversion device (not shown) toremove voltage spikes and the like that can be found in line voltage.The blade 540 connects to a mounting bracket 548 that, in the depictedembodiment, is located aligned with a symmetrical axis of the lamp andconnected to the Edison base.

To allow for the ingress of cool air and the egress of hot air, a filter554 covers a vent or vents formed in the enclosure 512. The filter 554can also be located where the Edison base 528 meets the bulb 512 and canbe attached to or integrally formed with the Edison base.

While the embodiments have been described with reference to such termsas “upper,” “lower,” “above” and the like, these terms are used forbetter understanding of the embodiments with respect to the orientationof the figures. These terms do not limit the scope of the invention.Furthermore, certain components of the embodiments have been describedwith reference to their location in comparison to other components.These descriptions should not limit the invention to only thoseconfigurations described. Preferred embodiments have been described,obviously, modifications and alterations will occur to others upon areading and understanding the preceding detailed description. It isintended that the invention be construed as including all suchmodifications and alterations as so far as they come within the scope ofthe claims, and equivalents thereof.

1. A lamp system comprising: an enclosure; an LED disposed in theenclosure; a synthetic jet actuator at least partially disposed in theenclosure for generating a current of fluid to cool the LED; and powerconditioning circuitry in electrical communication with the LED and thesynthetic jet actuator, the circuitry being configured to receive sourcepower from a source and to deliver a first power to the synthetic jetactuator and a second power to the LED.
 2. The system of claim 1,wherein the first power includes AC voltage and the second powerincludes DC voltage.
 3. The system of claim 1, wherein at least aportion of the circuitry is located on a printed circuit board at leastpartially disposed in the enclosure.
 4. The system of claim 1, whereinat least a portion of the circuitry is located outside of the enclosure.5. The system of claim 1, wherein the enclosure includes a translucentbulb.
 6. The system of claim 5, further comprising an Edison baseconnected to the bulb, the circuitry being in electrical communicationwith the Edison base.
 7. The system of claim 1, further comprising atleast one opening formed in the bulb.
 8. The system of claim 7, whereinthe at least one opening is covered by a filter.
 9. The system of claim1, wherein the synthetic jet actuator includes a first plate, a secondplate, a flexible material connecting the first plate to the secondplate and at least one opening defined by at least one of the firstplate, the second plate and the flexible material.
 10. The system ofclaim 9, wherein at least one of the first plate and the second plateincludes a shim and piezoelectric material contacting the shim.
 11. Alamp comprising: an enclosure including a translucent portion; anelectrical connector attached to the enclosure, the connector beingconfigured to electrically connect to an external power source; an LEDdisposed in the enclosure and in electrical communication with theelectrical connector; and a synthetic jet actuator in electricalcommunication with the electrical connector and arranged in theenclosure to generate a fluid current to cool the LED.
 12. The lamp ofclaim 11, wherein the enclosure includes a vent through which fluid isable to flow.
 13. The lamp of claim 12, wherein the enclosure includesat least two vents.
 14. The lamp of claim 13, wherein at least one ofthe vents is covered by a filter.
 15. The lamp of claim 11, wherein theelectrical connector includes a vent through which fluid is able toflow.
 16. The lamp of claim 11, wherein at least a portion of theenclosure is coated with a phosphor material.
 17. The lamp of claim 11,wherein the electrical connector includes at least one of an Edison baseand a bi-pin connector.
 18. The lamp of claim 11, further comprisingpower conditioning electronics in electrical communication with thesynthetic jet actuator, the LED and the electrical connector, the powerconditioning electronics being configured to convert a higher voltagepower from the electrical connector into a lower voltage power that isdelivered to the LED.
 19. The lamp of claim 18, wherein at least aportion of the power conditioning electronics reside on a printedcircuit board and the LED mounts to the printed circuit board.
 20. Thelamp of claim 18, wherein at least a portion of the power conditioningelectronics reside on a first printed circuit board and the LED mountsto a second printed circuit board, the first printed circuit board beingin electrical communication with the second printed circuit board. 21.The lamp of claim 20, wherein the synthetic jet includes at least twoopenings, a first opening being for directing a fluid stream generallytowards the first circuit board and a second opening being for directinga fluid stream generally towards the second circuit board.
 22. The lampof claim 11, wherein the enclosure includes a reflector and atranslucent cover.
 23. The lamp of claim 11, wherein the enclosureincludes a translucent bulb.
 24. An LED light assembly comprising: anLED; a synthetic jet actuator disposed with respect to the LED forcreating a fluid current to cool the LED, wherein the synthetic jetactuator includes a first plate, a second plate, a piezoelectricmaterial contacting at least one of the first plate and the second plateand a flexible hinge connecting the first plate and the second plate.25. The assembly of claim 24, further comprising a housing including atranslucent portion, the LED and the synthetic jet actuator beingdisposed in the housing.
 26. The assembly of claim 25, wherein thehousing comprises a translucent bulb.
 27. The assembly of claim 25,wherein the housing includes a reflector.
 28. The assembly of claim 25,wherein the translucent portion is coated with a phosphor material. 29.The assembly of claim 24, further comprising an Edison base inelectrical communication with the LED and the synthetic jet actuator.30. The assembly of claim 29, further comprising circuitry in electricalcommunication with the Edison base for delivering AC power to thesynthetic jet and DC power to the LED.
 31. The assembly of claim 30,wherein at least a portion of the circuitry is disposed on a printedcircuit board.
 32. The assembly of claim 31, wherein the LED mounts tothe printed circuit board.
 33. The assembly of claim 31, wherein theprinted circuit board is a first printed circuit board and the LEDmounts to a second printed circuit board that is in electricalcommunication with the first printed circuit board.
 34. The lamp ofclaim 33, wherein the synthetic jet includes at least two openings, afirst opening being for directing a fluid stream generally towards thefirst circuit board and a second opening being for directing a fluidstream generally towards the second circuit board.